The present application relates to improvements in honeycomb structure assemblies such as the cooling structures disclosed in my earlier U.S. Pat. No. 4,642,993 issued Feb. 17, 1987, the disclosure of which is hereby incorporated by reference thereto.
The cooling structures or walled heat exchange structures of U.S. Pat. No. 4,642,993 represent a substantial advance of the art by providing lightweight, inexpensive efficient structures which are relatively simple to manufacture and which permit inspection for quality control purposes during manufacture. The cooling structures of the Patent comprise opposed walls forming therebetween an interior space containing a honeycomb structure, the walls of which extend substantially perpendicularly or radially relative to the opposed walls, depending upon whether the walls are planar or curved.
The honeycomb structure of U.S. Pat. No. 4,642,993 is formed by joining narrow undulated metal strips to each other in an alternating down-and-up or stepped configuration to form a unit having a plurality of honeycomb cells, such as hexagonal cells, the walls of each cell which are formed by the "down" undulated strip extending from the base upward but being short of the top surface of the honeycomb structure, and the walls of each cell which are formed by the "up" undulated strip extending from the top surface of the honeycomb structure but being spaced from the base thereof. Thus, when the honeycomb structure is confined between a base wall and a top wall to form a honeycomb structure assembly, each honeycomb cell is open adjacent the base wall by uniform openings in the cell walls formed by the "up" undulated strip, and is open adjacent the top wall by corresponding uniform openings in the cell walls formed by the "down" undulated strip.
According to U.S. Pat. No. 4,642,993 the base of the honeycomb structure is attached to one wall of the walled cooling structure, such as the interior wall of a combustor liner, by welding or brazing the "down" undulated strips thereto, and the opposed wall, such as the exterior wall of a combustor liner, is wrapped thereover, and fastened to the interior wall by means of spaced spring clips and bolts passing through some of the honeycomb cells. This permits the heat exchange structure to be bent into a curved or annular configuration, prior to insertion of the clips and bolts, to form a unit, or a plurality of arcuate sections which can be assembled as a unit, to form a heating or cooling structure of the desired wall shape. Cooling or heating fluid entering the structure, such as air, is caused to undulate against one wall, such as the interior wall, to enter a honeycomb cell, and then against the other wall, such as the exterior wall, to escape from that honeycomb cell to adjacent cells where the undulation flow pattern is continued to effect cooling or heating of both walls, depending upon the nature and temperature of the fluid.
While the novel walled structure of U.S. Pat. No. 4,642,993 provides substantial areas of improvement over prior known structures it does have limitations relative to overall strength and reliability which preclude or restrict its use in certain important applications. For example, since only the "down" undulated strips are attached to the interior wall, such as by brazing or welding, the assembly does not have any resistance to high internal pressure. Even if the "up" undulated strips are brazed or welded to the exterior wall, the strength of the assembly is dependent upon the attachment of the "up" and "down" undulated stripe to each other and upon the integrity of the weld or braze connecting the edge of each undulated strips to the interior or exterior wall. Moreover, the manufacture of the honeycomb structure of the Patent requires the precise stepped alignment of the undulated strips while they are brazed to each other in order to insure the uniformity of the coolant passageways or gaps, and assembly requires thin line welding or brazing of the strip edges to the interior or exterior walls, which is possible but requires expensive machinery and skilled operators.
Thus, the present invention is concerned with novel honeycomb structure assemblies which have the advantages of those of U.S. Pat. No. 4,642,993 but which are stronger and more reliable under the effects of the conditions of the use. In addition, the present invention provides novel honeycomb cooling structure assemblies which are easier and less expensive to manufacture, avoiding some of the precision alignment means and skill required for the manufacture of the products of the Patent.